Process for treating viscose rayon yarn



Jam 1963 H. FRITZEMEIER EIAL 3,073,

PROCESS, FOR TREATING VISCOSE RAYON YARN Filed March 23, 1960 HARKE FRITZEMEIER. HENDRIKUS JOHANNES LEIJSER IN VEN TORS BYMf ATTORNEY United States Patent Ofifice 3,073,003 Patented Jan. 15, 1963 ware 1 Filed Mar. 23, 1960, Ser. No. 17,110 Claims priority, application Netherlands Apr. 9, 1959 5 Claims. (CI. 28-76) This invention relates generally to a process for treating viscose rayon yarn, and more particularly to a process for stretching viscose rayon tire yarn, as well as the resulting yarn.

In the prior art, viscose rayon tire yarn is stretched by passing the yarn through an excess of lubricant which moistens the yarn. Thereafter the yarn is stretched at room temperature and dried. It can readily be seen that such a process requires an expensive and time consuming drying operation. In addition, the drying is required because the moist yarn will shrink with an attendant increase in elongation, thereby defeating the purpose of the stretching operation.

An alternative procedure is to omit the moistening of the yarn prior to stretching. However, this is also an undesirable process because there are many thread breaks which lower the quality of the yarn. It has also been proposed to omit the lubricating step; however, it was found that the yarn was fibrous, which indicates filament breakage.

It is therefore an object of the present invention to provide a process for treating viscose rayon yarn that is free of the diificulties of the prior art.

It is further object of this invention to provide a viscose rayon tire yarn of low elongation.

A further object of this invention is to provide a process for treating viscose rayon tire yarn wherein drying after stretching is eliminated.

It is an additional object of this invention to provide a process for stretching viscose rayon tire yarn wherein thread or filament breakage is substantially reduced.

An additional object of this invention is to provide a viscose rayon tire yarn of low elongation, low average moisture content, and one that has been stretched at room temperature.

. These and other objects will become apparent from a reading of the following detailed description taken in conjunction with the accompanying drawing in which:

The FIGURE is a perspective view of an apparatus by which this invention may be practiced.

The objects are accomplished by conditioning viscose rayon yarn to an average moisture content of 12 to 14%. Thereafter a conventional textile finish or lubricant is uniformly distributed on the yarn. The lubricated yarn is then stretched at room temperature. The process yields a viscose rayon tire yarn which has an elongation of to an average moisture content of 12 to 14%, and which yarn contains a small amount of a lubricant.

The stretching of the conditioned and lubricated yarn is carried out at room temperature. In other words, the yarns are not heated by external applications of heat such as in steam stretching. The yarn may be stretched by passing the yarn a plurality of times around a grooved supply roller and thence a plurality of times around a grooved draw roller. The draw roller is operated at a hi ;her peripheral speed than the supply roller. If desired, more than one supply or feed roller and draw roller may be used, as for example, a pair of supply rollers and a pair of draw rollers may be provided without departing from the spirit and scope of this invention.

It is also possible to stretch the yarn by passing it over a pair of freely rotatable or positively driven rollers having portions of different diameters. In the simplest operation, each roller has two portions, wherein the yarn passes several times over that portion of the smaller diameter and thereafter to the portion of the larger diameter. The yarn is stretched by passing from the smaller diameter to the larger diameter. In addition, the pair of rollers instead of being stepped may be conical in shape, thereby stretching the yarn gradually as it passes from the tip of the cone toward the base thereof.

As pointed out above, if the yarn is conditioned to a moisture content of 12 to 14%, contains a uniformly distributed lubricant, and has been stretched at room temperature, the elongation of the yarn will be reduced from 15 to 25% to about 10 to 15%. -Also, the number of thread and filament breaks which normally occur during the stretching operation will be substantially reduced, and may even be eliminated. In addition, the costly and time consuming drying operation is eliminated.

The yarn may be conditioned to the desired average moisture content by any conventional means, as for example, by maintaining the yarn in an atmosphere of controlled temperature and humidity for a period of time sufiicient to yield the desired average moisture content. One such method is to retain the yarn for six days in an atmosphere maintained at 20 C. and relative humidity.

It is essential to the successful operationof this invention that the yarn be conditioned to an average moisture content of 12 to 14%. It has been found that the more non-uniform the moisture content, the more the threads will break. Thus it is preferred that the moisture content throughout the yarn be as uniform as possible. This is especially true when the average moisture content approaches the lower acceptable limit of 12%. It should be noted that at the higher limits, the moisture content throughout the yarn is not as critical.

Thus, in those situations where the average moisture content is approximately 12%, it has been found that a variation of much more than 1% from this figure for the moisture content throughout the yarn will result in an increase in thread breakage. Therefore, it is preferred that when the average moisture content is about 12%, the moisture content throughout the yarn be not less than about 11%, and not more than about 13%. However, if the average moisture content is about 14%, then a variation of 1.5% in the moisture content throughout the yarn is acceptable.

It is believed that the critical average moisture content is the result of the relationship between the load to which the yarn is subjected and the resulting elongation. If this relationship is plotted with the load along the vertical axis and the elongation on the horizontal, a curve ascending sharply from zero will be obtained. This curve will break sharply at some point above the horizontal axis. This deflection in the curve represents the point at which the yarn breaks. If similar curves are plotted for yarns of different average moisture content which are above the 14% limit, the breaking point will be lower.

It is believed that such is the result of the tension which is applied during the stretching. Normally the tension applied to the yarn during the stretching will be about half that which is required to break the yarn of the prescribed average moisture content. However, where the average moisture content is too high, the ten sion required to break the thread is less than that required to break the yarn of the prescribed moisture content. Therefore, the normal tension applied will approximate and may even exceed that which will break the yarn.

If curves are plotted for different average moisture contents which are below the 12% limit, the breaking point of the yarn will also be lower. This is believed to be the result of dry yarn being less elastic than a moist yarn. In the normal stretching operation, a constant differential between the speed of draw-off from the stretching operation and the speed at which the yarn is supplied to the stretching operation is maintained. For yarns of the correct average moisture content, this produces a constant stretching tension.

When a low moisture content portion passes through the stretching operation, the tension is insufiicient to stretch the dry yarn to the same degree as the correct moisture content portion, because it requires more tension to stretch a dry yarn than it does to stretch a moist yarn. There will be an accumulation of tension because there willbe less decrease in the tension when applied to this yarn than when applied to the desired yarn. Therefore, the accumulation of tension will soon reach a point where it breaks the yarn.

Thus it can be seen that the average moisture content of the yarn must remain within the defined limits and that the moisture content throughout the yarn should not vary fromthe prescribed limits if a first quality tire yarn is to be produced.

As pointed out above, it is essential to the successful operation of this invention that the yarn contain a uniformly distributed lubricant. It is preferred that a nonaqueous and homogeneous lubricant or finish be used because it has been found that the aqueous emulsions are sometimes difiicult to apply uniformly to the yarn. In those situations Where the aqueous emulsions may be uniformly applied, there is normally an excess of lubricant used, thus adding materially to the cost of the operation. Any conventional tire yarn lubricant or finish may be used without departing from the spirit and scope of this invention. Examples of these lubricants are sold commercially under the trade names of Nopco and Stantex. They are a solvent refined mineral oil and a solvent extracted sulfonated mineral oil mixture, and a vegetable oil sulfonate, respectively.

The uniform distribution of the lubricant may be obtained by any conventional means. For example, it is possible to treat the packages of tire yarn prior to the first drying with the lubricant in an aqueous emulsion. This is usually the last'step in the conventional aftertreating process for cakes of viscose rayon tire yarn. The cakes are then dried, and it' has been found that the lubricant is distributed on the yarn in a sufficiently uniform manner. However, in such a process, circulation of the aqueous emulsion is required which necessitates an excess quantity of lubricant, thereby increasing the cost of the operation.

It is, therefore, preferred to contact the yarn with only that quantity of lubricant which may be absorbed by the yarn. It has been found in these situations that more uniform distribution is obtained if a non-aqueous and homogeneous lubricant is used. This is because a nonuniform distribution of lubricant results in the same difficulties as that found for excessive variations in moisture content'throughout the yarn, that is, excessive thread breakage. A non-uniform distribution will result in a variation in the moisture content of the yarn with the same result as pointed out above for variations in moisture content.

The non-aqueous lubricant may be applied to the yarn by several methods. For example, the yarn may be -caused to contact a finishing roller to which is applied the non-aqueous lubricant. This will result in uniform distribution of the lubricant on the yarn, and at the same time, will contact the yarn with approximately that amount which may be absorbed by the yarn. The lubricant maybe supplied to the finishing roller by any conventional method, such as by immersing a portion of the roller in the lubricant, or by supplying it to the roller surface from a tube.

It is preferred to apply the lubricant to the yarn by passing the yarn through a small channel or tube to which the lubricant is supplied. The lubricant is supplied to the channel or tube in that quantity which the yarn can absorb at the speed at which the yarn passes through the tube. The channel or tube should preferably have an internal diameter of not more than 1 mm. In addition, the lubricant should be supplied to the channel or tube through a capillary. This will insure that the lubricant is uniformly distributed throughout the yarn.

The lubricant supplied totheyarn should be in sufficient quantity whereby the yarn will absorb about 0.1% to 1.5% by weight of the lubricant, and preferably at least 0.2%. The amount to be supplied to the channel or tube can be easily determined by methods known to those skilled in the art.

The tension applied to the yarn may vary within rather wide limits as it is determined by the elongation of the yarn prior to stretching and the desired elongation. The

determination of the amount of tension to be applied can easily be made by methods known to those skilled in the art. For example, a yarn of an 1854 denier prior to stretching and an elongation of 22% will require about 3000 to 4000 grams tension if a yarn of an elongation of about 13% is to be obtained.

Reference should now be had to the drawing for a detailed description of an apparatus'capable of carrying out the process of and producing the viscose rayon tire yarn of this invention. Reference numeral 1 indicates generally a stretching device comprising two stepped rollers indicated generally at 2 and 3, respectively. Rollers 2 and 3 are mounted on freely rotatable shafts 4 and 5, respectively. It should be understood that shafts 4 and 5, while illustrated as freely rotatable, may also be positively driven at the same or different speeds without departing from the spirit and scope of this invention.

Rollers 2 and 3 each comprise two portions or steps. Roller 2 has two steps 6, 7 and roller 3 has steps 8, 9. These rollers are of substantially the same diameters with steps 6 and 8 being smaller in diameter than steps 7 and 9. Peripheral grooves 10 are provided on steps 6, 7 and peripheral grooves 20 are on steps 8, 9, which grooves define the path of yarn 11 around rollers 2 and 3.

Yarn 11 of the desired average moisture content of 12 to 14% is drawn ofi supply package 13 through guide 12 into and through inclined tubular channel 18 having an internal diameter of 1 mm., and a length of 15 cm. A conventional lubricant is supplied from a source (not shown) through a capillary tube 19 having an internal diameter of 1 mm. to the lower end 21 of channel 18. The lubricant is supplied in an amount sufficient to be substantially completely absorbed by yarn 11 as it passes through channel 18 in contact with the lubricant.

After leaving channel .18, yarn 11 is guided by guide 14 onto the first grooves 20 of step 8 on roller 3. Thereafter the yarn is passed through grooves 10 and 20 of steps 6 and 8, respectively, as is more clearly shown in the figure. After leaving the last grooves 10 and 20 of steps 6 and 8, the yarn is passed in a similar manner over grooves 10 and 20 of steps 7 and 9 of rollers 2 and 3, respectively. By passing from steps 6 and 8 to steps 7 and 9, yarn 11 is stretched, as for example, about 14%. From groove 10 of step 9, yarn 11 passes through guide 15 to a traversing thread guide 16 thence to rotating package 17 on which yarn 11 is wound. The rotation of package 17 pulls the yarn 11 through the above described apparatus from package 13. It should be. understood that any winding device may be used, and also the yarn may be pulled from package 13 by positively driven rollers.

For further illustration of this invention, the following specific example is offered. It should be understood that the same is offered merely for the purposes of illustration, and should not be considered as limiting the scope of this invention.

Example A package of viscous rayon yarn of an unstretched demer of 1854, a strength of 4.4 grams per denier, and

an elongation of 2291. was conditioned throughout to an average moisture content of 12% by maintaining the package for six days in an atmosphere maintained at 20 C. and a relative humidity of 65%. The deviation of the moisture content from the 12% average was lesS than 1%.

The yarn was drawn oil the package 13 at a speed of 300 meters per minute and passed through channel 18 having a length of 15 cm. and an internal daimeter of 1 mm. A lubricant commercially available under the trade name Stantex, which is a vegetable oil sulfonatc, was supplied through capillary tube 19 to channel 18 whereby it was absorbed by the yarn passing through channel 18. The supply of the lubricant was adjusted in order that the yarn leaving channel 18 contained about 1.0% by weight of lubricant.

The impregnated yarn was thereafter led around stepped rollers 2 and 3 in the same manner as shown in the figure. Steps 6 and 8 each were of a diameter of 46.5 mm., and steps 7 and 9 each had a diameter of 53.2 mm. As a result, the yarn was stretched 14%, after which the yarn was wound into a bobbin under a tension of 100 grams. During the stretching the yarn was subjected to about 4000 grams tension.

The yarn had a strength of 8.2 kg. and an elongation of 13%. The yarn was not fibrous and relatively few breaks occurred in the processing. A cord manufactured by conventional means from this yarn had a strength of 16.0 kg., whereas a yarn which had been stretched in the presence of steam had a strength of 15.5 kg.

A yarn which had not been conditioned to the average moisture content of 12 to 14% and which did not contain a uniformly distributed lubricant was stretched by the same type system. The yarn thus obtained was fibrous and many breaks occurred in processing.

It can readily be seen from the foregoing that this process produces a yarn of reduced elongation and one which is not fibrous. In addition, relatively few breaks occur during the processing of the yarn by this invention.

It should be understood that many modifications may 40 be made in this process without departing from the spirit and scope of this invention. For example, any conventional viscose rayon tire yarn lubricant may be used. This invention is to be limited only by the following claims.

What is claimed is:

1. A process for aftertreating viscose rayon yarn com prising the steps of:

(a) conditioning the yarn in package form to a substantially uniform moisture content selected from the range of about 12% to about 14%,

(b) passing the yarn from the yarn package to a lubrieating zone and uniformly lubricating the yarn with a small amount of a non-aqueous lubricant,

(c) stretching the yarn at room temperature, and

(d) collecting the stretched yarn in package form.

2. A process for aftertreating viscose rayon yarn comprising the steps of:

(a) conditioning the yarn in package form to a substantially uniform moisture content selected from the range of about 12% to about 14%,

(b) passing the yarn from the yarn package to a lubricating zone and uniformly lubricating the yarn with about 0.1% to about 1.5% by weight of a nonaqueous lubricant based on the weight of the yarn,

(c) stretching the yarn at room temperature until the elongation of the yarn has been reduced to about 10% to 15%, and

(d) collecting the stretched yarn in package form.

3. The process of claim 2 in which the maximum deviation of the moisture content throughout the yarn is 1.5%.

4. The process of claim 2 in which the maximum deviation of the moisture content throughout the yarn is 1.0%.

5. The process of claim 2 in which the yarn is lubricated with at least 0.2% by weight of a non-aqueous lubricant.

2,218,504 Cadden Oct. 22, 1940 Campbell Aug. 19, 1958 I 

1. A PROCESS FOR AFTERTREATING VISCOSE RAYON YARN COMPRISING THE STEPS OF: (A) CONDITIONING THE YARN IN PACKAGE FORM TO A SUBSTANTIALLY UNIFORM MOISTURE CONTENT SELECTED FROM THE RANGE OF ABOUT 12% TO ABOUT 14%, 